Companies have very different definitions of control. Syngenta, the maker of Tenacity, tends to be extremely careful about claiming their products control something. Globe thistle also isn't listed, but I can tell you that it's the most effective herbicide on it I've ever found.

Tenacity DOES kill P. annua, but the kill isn't perfect and doesn't happen in one spray. So they don't make that claim.

Practice is very different and seems to depend on a large number of factors. I get P. annua and P. trivialis, and find that Tenacity controls both extremely well. Others report lesser results with both species.

Tenacity alone can take care of poa triv? I hit it multiple times last year and it came right back this spring. Maybe I'm doing something wrong

It can, yes. In my case, this was not a good year. I have uncountable outbreaks of P. triv and four or five small patches of P. annua. The P. triv is single leaf at the moment, but you know how that stuff goes.

I shot the triv yesterday before the rain, with enough time to soak in. The P. annua is on its second shot. The triv will die fast, the annua will probably require one or two more light taps before it goes down for the year.

I find that Tenacity works best with soft water, so I sometimes suggest using a gallon of cheap distilled water from your grocery store in the sprayer.

I also enhance it with 1 oz DMSO per gallon, but I don't generally recommend that to others. You have to wear long pants and shirt, and must make absolutely certain that not a single drop touches your skin because the DMSO will make it absorb into you just as easily as into the plant.

Ok good to know. I'll try the distilled water. Think I'll skip the DMSO partly because it sounds like something Mr. White from Breaking Bad whips up.

DMSO is dimethyl sulfoxide.

It's a by-product of the paper industry, and recognized by its unmistakable garlic flavor seconds after touched to the skin (it's not ingested). It's harmless in reasonable amounts in and of itself and used in veterinary medicine, most notably to give medications to horses, who are difficult to dose and cannot vomit if something is wrong.

It has the interesting effect of carrying any other organic molecule along for the ride, hence the use in medicines.

Unfortunately, it'll also carry the herbicide right through your skin, so caution is absolutely required.

Since I'm used to handling concentrated nicotine solutions in PG as well as pH 13.8 - 14 and super-saturated lye solutions, I know how to work with it and not get hurt.

Sounds like good stuff. If I can't get rid of triv I may cautiously give it a try

I just ordered Bonide Turbo Spreader Sticker - do I need to be as afraid of that that as your DMSO? I wear long pants and long sleeves when I spray Tenacity, but I've been known to get a drop or two on my hands once in a while (which I promptly rinse off).

Hoganjr: If you do, wear long pants, long shirt, and wear gloves. Don't apply on a windy day. If you taste garlic, stop immediately and head for the shower instantly--and take a cool one.

Timtsb: Spreader sticker is just surfactant with no penetrating ability. Normal precautions are entirely sufficient when using that with Tenacity.

Both of you: On the up side, Tenacity does hold the Least Toxic certification (a rarity among herbicides), so the risks aren't nearly as severe as using (say) Weed B Gon Crabgrass Control with DMSO. Which I would never do. I restrict DMSO usage to pure glyphosate and Tenacity.

ok thanks

I'm a little confused over here. There is definitely some poa annua in my lawn (exhibit A)

I was worried that I had an all out infestation because there are seed heads throughout my lawn, but with the exception of the obvious spots (such as above) I don't see any color differentiation, even after spraying Tenacity. (exhibit B)

So do I have a poa (or other) problem, or are there turfgrasses that seed even when cut regularly (to approx 3")?

Turfgrass can seed at 3" easily; mine does so regularly, sometimes even as heavily in patches as your photos show.

Off the cuff, that doesn't look like P. annua or P. trivialis. The color is completely wrong.

Morph, are you saying the second photo doesn't look like poa? But the first does? These seed heads are very obvious now...my lawn looks pretty bad. I really hope it's just the turfgrass and another mowing or two will end it. One thing that's worrying me is non of the neighbors yards are doing this...why mine but not theirs?

Neither looks like P. triv or P. annua, so that's good!

Healthy lawns produce more seedheads (conversely, healthy but lightly stressed lawns go nuts with the seedheads, so it does vary). Lawns that are never fed usually don't do it as they can't muster the energy when they're kept short.

Year by year, my seedhead count varies. This year, almost none. Two years ago, everywhere and in large areas. And yes, they're unattractive, but don't last for too much longer.

Ah, yes - about regular turf seed production...

While we don't care for cultivars that generate lots of seed, those cultivars that do are the only ones that the seed producers keep producing. I have a monostand of the low seed-producer call Emblem, but they stopped selling it because they couldn't make enough money producing the seed for sale. I have a different cultivar in the backyard monostand - Blueberry. It is a much more prolific seed producer. Guess which is still in production?

Despite what I'm being told I am pretty much giving up hope that all these seed heads are coming from my turfgrass. I've been researching poa annua a little bit more and images I see online look very much like what I have going on in my lawn. Here are a few more pictures of my lawn...

Opinions?

If it is poa annua (I'm convinced that it is), I can't for the life of me figure out why this is happening. My lawn was started from seed in September 2013. I didn't have any poa annua problems in 2014 (nor any of these seed heads). I mow high and I water infrequently. And the kicker is I see nothing like this in any of my neighbors lawns, none of whom take lawncare seriously...so why would it take hold in my thick, high lawn but not in theirs? Was it mixed into the seed the landscaper used but didn't take hold until now? I overseeded last Sept but I know it wasn't in that seed because I had a few bare spots I fixed and those spots are free of these seed heads.

And what do I do about it? Kill everything and restart? Keep spraying Tenacity in hopes I beat it? Or, since it's an annual, will it all die this summer, then use preemergents more aggressively?

OK, now that's starting to look more like P. annua.

The stuff sprouts in fall, but frequently nobody notices it. It's small. Then it goes nuts in spring. Undoubtedly it was in your overseeding.

Keep spraying the Tenacity. Definitely don't water more often than once a week in summer, which will at least set it back. And keep your pre-emergent layer up and running through fall as the seed bank is still there, waiting.

That was my first thought but there are multiple spots where I scalped down to bare soil and reseeded and there's not a single patch of poa annua in any of those spots. Whatever... How it got there doesn't really matter now. So you think I'll be able to recover from this? Does it really die off? And keeping Preemergents down continuously is more important than letting it lapse at the end of summer to overseed again to keep my turf thick?

I really thought I was getting the hang of lawn care but I'm feeling totally defeated. This has taken wind out of my sail...no longer proud of my lawn.

I managed to recover from many large patches of P. annua. Where's that photo? Back then, Round Up was the only option. The grass spread closed by September (this photo was from June, about 2 months into the repair).

It really does die off; there's a reason it's called P. annua. It's an annual, although like any annual it can over-extend when conditions are compatible. Dry, hot conditions aren't compatible, particularly when the P. annua is Tenacity-stressed.

Your lawn has bluegrass, yes? Then also feed to make it spread this fall while keeping your pre-emergent layer up. Do the same in spring and it'll fix the holes.

une

Wow I guess if it can happen to Morph it can happen to anyone ;)

After mowing today I'm feeling less pessimistic... Although I know it's still there, the lawn looks much better. The shadows don't help, but here it is today:

I will keep up with my Tenacity applications and hope that there is enough KBG to fill in the holes when it dies. If not, could I put a small (1/2") layer of topsoil in any obvious holes and seed just those spots in Sept even with after a full strength Prodiamine application (put topsoil/seed down after application)?